Plastic resinous material and process of making same



Patented Nov. 20, 1928. 1,692,524 UNITED STATES PATENT OFFICE.

HARRY 1!. WEBER, OF MONTCLAIR, NEW JERSEY, ASSIGNOR TO ELLIS-FOSTER COM- PANY, A CORPORATION OF NEW JERSEY.

PLASTIC RESINOUS MATERIAL AND PROCESS OF MAKING SAME. No Drawing. Application filed January 12, 1924 Serial No. 685 887.

This invention relates to a plastic molding ing compositions, and for various other reacomposition or laminated press board comsons, that cresol, as stated, could not by itself prising respectively appropriate billing or be used to meet the commercial requirements sheet material incorporated with a cresylate of the present time unless it be admixed with resin binding agent. aconsiderable amount of phenol in the prepa- 00 The type of molding composition of the ration of resinous condensation products present invention is one which when hot formed 1n the presence of a. restricted amount pressed i t i iti ll a high degree of of alkaline catalyst. This requirement ma flowability followed by a. curing eifectresulthave been necessary under former methods of ing in a product which even when hot is rigid preparation which involve reacting on pheas w nohc bodies with formaldehyde in the pres- Th present i ti i it br d aspects ence of an alkaline catalyst not in excess of a relates to a method of making molding comsmall fraction of a molecular proportion of ositions from phenolic substances generally the phenolic body employed. Prior investiut in its specific aspects, which will be pa-rgators as well as others have generally used ti l -l emphasized in the present applicaa base 111 small or what may be termed catation, it relates tocompositions containing a lytlc l'opol'tlons. In the present inventi n resinous binder prepared from ci-e;ol (cresylic I pre er to employ large quantities of a base, acid, tar acid, etc.), a basic substance, and Which by following the proceduresIhave laid 2.) formaldehyde or equivalent substance. down herein, makes possible the successful For the purpose of comparison in order to employment 9f the cheaper CIGSOlS in place Of indicate the improvement which I have made phenol meeting the very exacting commercial i thi t I t k occasion t refer t ty requirements established in the molding field. of resinous binder made from phenol and for- Instead of obtaining from cresol the ex- 2 maldehyde in the presence of a restricted pccted inferior molding composition I obamount of a catalyst. Products of this sort tain one which in some respects has superior have been used to a large extent commerqualities and this is accomplished wlthout cially. In making these products it is custhe addition of any phenol whatsoever theretomary to use phenol as the sole phenolic body by resulting in a substantial saving in cost 30 or to use a large proportion of phenol, toof manufacture. Molding compositions havll gether with some cresol. Increase in the cremg the properties of my product enjoy a field sol content beyond a certain amount usually of use which expands very ra idly, in fact in results in complaints by the molder supplied great disproportion as the price of the mold with such inferior material. Although seving composition is reduced. Hence I be- 35 eral processes and patents refer to composilieve the use of cresol in the manner which I tions made from phenol and cresol, or cresol am about to describe constitutes an improve- (cresylic acid) is stated casually to be the ment of great value in that it develops a much equivalent of henol, as a matter of fact, the wider field of utility for molded products. products ma e from phenol alone, because I do not in all cases exclude the possibility m of their reactivity, good flowing qualities and of using phenol to some extent, provided it for other reasons, have come tobelooked upon is not present in such an amount as to deas important if not es ential elements of such tract from the properties of my product. molding compositions, adequate to meet the The presence of phenol as an impurity in the demands of present day commercial molding. cresol is not objectionable. While I prefer 4.3 For a considerable number of years phenol as stated to use cresol alone I do not wish 1 has been available cheaply due to an excess my process to be evaded by anyone who seeks of war supplies. But t is source is now to do this by the addition of some phenol as practically at an end and to meet the demand there are certain features of the invention for phenol it probably will have to be made which do not relate to the kind of phenolic so by synthetic processes at a cost much greater body employed but to methods of incorporatthan that of phenol under normal conditions ing or reacting on the materials irrespective in years past. of their phenolic nature in order to produce On the other hand cresol (cresylic acid) is compositions capable of meeting the very available in large quantities. It has been supspecific and exacting requirements of com- 65 posed, because of its uncertain efiect in moldmercial molding plants.

cresols and I may With respect to the cresol employed it may be noted that a mixture of meta and para cre' sol, well known in commerce vas metaparacresol and containing these two constituents in proportions which usually range from l0 per cent of one to 60 per cent of the other 1s especially serviceable. However metaparacresol is more expensive than mixtures of the three cresols, that is the ortho, meta and para also employ a commercial mixture known as tar acids having a content of say 97-99 per cent of phenolic bodies. The use of these cresols in conjunction with some of the xylenols also is feasible.

The alkaline material which I may employ for example in full molecular proportion is one which preferably will combine with the cresol to form a cresylate. Thus 1 may use proportions of materials which will form for example the cresylates of barium, or calcium, strontium, magnesium and the like. Preferably I employ magnesium oxide or hydrate.

In the first place I prefer to employ heavy magnesium oxide or calcined magnesium carbonate of a heavy character rather than the very light pharmaceutical type of magnesium oxide on the market. Preferably this heavy magnesium oxide is ground in a ball mill with formaldehyde to bring about a certain reaction, the nature of which is not entirely clear but which apparently involves the hydration and change in the magnesium material with apparent reaction to some extent with the formaldehyde itself. When this heavy oxide of magnesia is mixed with formaldehyde solution the oxide settles almost immediately. On grinding the magnesia and formaldehyde solution in a ball mill 2. milk or cream is obtained. When prepared in the preferred manner this milk or cream on standing will thicken forming a paste or jelly. Grinding magnesium oxide or analogous base in formaldehyde solution or in some cases in cresol forms a specific preferred feature of the present invention.

Magnesium oxide material or calcined dolomite ground in aqueous formaldehyde is the form I preferably employ for reaction with the cresol. Thus formaldehyde solution, that is the ordinary commercial 40 per cent grade, may be mixed with magnesium oxide in proportions such that there will be one mol. of magnesium compound calculated as magnesium oxide to one mol. of cresol employed in reaction mixture used for making the resin. The proportion of the formal dehyde of this strength to the cresol may he say 90 to 100 parts by weight for each 100 parts of cresol taken.

By grinding a mixture of magnesium oxide and aqueous formaldehyde under these conditions a product is obtained which may be mixed with the cresol and reaction allowed to proceed to the formation of the magnesium cresylate resin or equivalent resinous material obtainable according to my process.

While cresol, as stated, has been regarded as an uncertain sort of phenolic compound in comparison with phenol itself I have found its activity with a full mol. of the magnesium material prepared in this way to be extraordinarily great. The magnesium formalde hyde reagent is capable of bringing about reaction in a vigorous manner and of carrying it to a rapid conclusion yielding a resinous substance which is quite resistant to heat. Furthermore, contrary to expectations, this large proportion of so'vigorous a reagent does not yield the Worthless products which Baekeland has indicated to result.

Instead a hard tough fairly infusible resin is obtained, which is capable of binding together various-filling materials or sheets of paper to form molded products or laminated press board respectively of great value and made at a comparatively low cost of manufacture from materials which are freely available. The vigor'of the magnesium oxide material in its reaction with cresol and formaldehyde calls for a careful control over the operation which I will set forth hereinafter in great detail.

In view of the deficicnc of information available in the art I have etermined to provide a very full description of my process in order that anyone having the proper chemical knowledge can manufacture hereunder in a reasonable time molding compositions of excellent quality.

The problem which has offered me the greatest difiiculty and to the solution of which I have made an enormous number of experiments is that of producing flowability conjoined with rapid curing or setting.

Flowability is that softening and penetrating quality of the resinous binder under the influence of heat which is necessary in order to cover the particles of filler and cause a good impress or replica to be made. The resin should become very liquid and penetrating on heating.

Rate of setting-A composition which initially is readily flowable on heating but which will cure or set and become rigid in only a few minutes time hardly ever exceeding 6 to 10 minutes total time in the hot press and usually 5 minutes or less, is demanded for pieces of average thickness say to of an inch and if in addition. subsequent cooling in the press may be avoided an improvement results.

My observations and experiments led me to the conclusion contrary to what is taught by the prior art that cooling in the mold as a step in the molding operation can be eliminated in making articles prepared according to the present invention.

I have made compositions according to this invention which when hot pressed at ill) H ll

ture to be removed hot without 160 (J. for 3 to 5 minutes could be removed hot from the mold without the formation of blisters or any signs of warping. In short a rigid article free from blisters comes directly from the hot mold. It is true that products made from phenol and formaldehyde with a small amount of alkaline catalyst (which commercially by the way almost invariably includes hexamethylenetetramine) can be taken hot from the mold in a cured state and this is the practice to some extent but generally speaking the danger from ammonia blisters due to the use of hexamethylenetetramine and the possibility of warping makes the step of cold pressing desirable. Laminated press board offers even greater difficulty.

It IS not necessary in most cases to produce th a wholly in'l'usible product. If the fusing point of the resinous binder is substantially above that of the temperature of the mold the composition will serve the purpose of the molder in the majority of cases. If the prod uct is hard enough at the molding temperadanger of deformation so that the molder isable immediatel to extract the article from the hot mold an not have to wait for cooling, however slight, a saving in time is effected and in consequence the output from molds, which are necessarily expensive, is increased.

In the course of my experiments involving the production of many hundreds of molded pieces in accordance with the present invention I have never observed the formation of blisters on withdrawal of the molded specimen from the mold while still at the molding temperature. In any event the presence of ammonia from whatever source derived is responsible for blistering which I have observed takes place very readily when testing commercial samples of such molding composition in comparison with my own nonblistering product under like conditions.

In addition to preferring to have ammonia or hexamethylenetetramme absent from my molding composition because of the blistering action I also prefer to avoidthe use of watersoluble alkaliessuch as caustic soda or caustic potash. These have been recommended by DeLaire, Baekeland and others but I consider the presence of such water-soluble compounds to be detrimental in several respects. In fact any uncombined hexamethylenetetramine or similar compound remaining soluble in water even after protracted exposure to air is in my opinion objectionable. In the present invention preference therefore is given to the use of alkaline earth bases such as calcium or barium oxide or hydrate, these having the advantage that any free base in the composition on ex-, posure to air at the surface of the molded article will become carbonated to a water insoluble substance. While therefore with amcarbon ates.

monia and caustic alkalies even small amounts are deleterious for many purposes the case is different with bases forming water-insoluble These may be used in substantial proportions with the resultant advantage of quick curin,,,. Magnesium oxide or hydrate is in a class by itself since basic compounds of this nature are practically insoluble in water yet exert a peculiar and specific resinifying effect, which I consider remarkable in its character. The presence of a substantial proportion of magnesium hydrate is therefore beneficial in several respects.

Among other properties of interest I may note that the presence of a small amount of moisture is not detrimental to the molding qualities of the composition. I had expected at moisture would cause blisters in a manner similar to ammonia but I find this is not the case. I have allowed the molding composition in amoist state to dry over night simply by spreading it in a thin layer exposed to the air at room temperature. The next day, although feeling dry to the touch, con-' siderable moisture, for example 5 to 10 per cent, was present. Yet this composition molded well without disturbance in the mold and without blistering.

us when using my composition it does not become necessary to dry out the filler nor the composition itself to a high degree. For example ordinary commercial fillers such as china clay or ground wood containing a content of moisture such as may result from absorption of moisture from very humid air may be used without ditl'iculty. Ina similar manner it is not necessary to eliminate all traces of moisture from the resin. When the product is to be used for electrical insulating purposes a fairly dry composition of course is desirable. Furthermore a somewhat better surface finish is obtained when the composition is dry. The fact remains however that moisture does not cause the same molding difficulty that is brought about by the prcsence of ammonia. The percentage of culls or rejects by my process is I believe substa ntially lower.

In practically all plastic molding compositions 1t is customary to incorporate a filler in the composition. Fillers may be of a mineral nature, such as clay, talc, whiting, silica, asbestos powder or fibre or mica, or an organic filler may be used such as leather, hair, sawdust, especially a fine sawdust or ground wood sometimes called wood flour. Other organic fillers are cotton or silk flock or wood fibre.

ome organic fillers, such as hair or leather may require a reduction in molding temperature. In general, organic fillers should be molded at temperatures lower than is possible with inorganic ones. Since the filler is usually considerably cheaper than the hinder the cost of the composition is lowered in proportion to the amount of filler present. This lllU with the spreading or likewise may proportion of filler varies with its density and penetrating powers of the resin. A substance which is not porous such as china clay may be used in much larger proportion than an absorptive material like ground wood or infusorial earth.

The resin may be incorporated with the filler in various ways such as by the use of solutions. In the present invention when using an absorptive filler, e. g. wood flour I refer to incorporate the resin in such a way that the fibers are coated but not necessarily completely impregnated with the resin. The wood flour is much cheaper than the resin and the use of a maximum amount of the former is desirable on account of reduction in cost. By coating the fibres as for example by agitating the filler in a suitable apparatus of the type of a WVerner-Pfleiderer mixer an introducin the resin in a hot molten condition the fi res may be well coated without necessarily forcing the resin into the interior canals of this type of filler. Such a composition usually molds better in that the resin, when used in minimum proportion, appears to flow more freely and give a more exact impress and improved surface finish. Methods which involve impregnation of the fibre with alcoholic or of aqueous solutions of the resin or methods of working on hot milling rolls for long periods of time to bring about impregnation of the fibre, are not as useful, in my opinion, as the procedure I have described. I believe the coating of a porous particle without much impregnation thereby leaving an air cell may afford a structure which is superior in certain electricalapplications and elsewhere.

Sometimes however, especially when of a porous character, the filler may be impregnated by the use of a solution of the resin or by mixing on milling rolls such as are used in rubber milling operations and subsequently, if desired, the impregnated articles may be coated with a highly fusible and reactive resin.

In carrying out my process I preferably heat and agitate the raw materials without filler to bring about the formation of a resinous substance which is fairly soft when cold but moderately liquid when hot, being made preferably from aqueous formaldehyde, in order to save the cost of using more expensive forms of this material. The water of the formaldehyde solution should be largely removed and this preferably may be done by drying the resinous material in a vacuum dryer. The hot liquid resin is then preferably incorporated with a filler, which be hot, in a powerful mixing apparatus. be heated if desired.

The preparation of the resin involves the consideration of many variables. For example in carrying out my process I have The latter may found the following variables should not be disregprded.

1. ind of pheno ic body employed.

2. Kind of basic material.

3. Proportion of basic material.

4. Proportionof formaldehyde.

5'. Time of heating of the reaction mixture.

6. Temperature of the reaction mixture.

7. Time of drying of the resin.

8. Temperature of drying of the resin.

9. Effect of filler.

10. Proportion of filler.

These variables all require consideration and adjustment with respect to each other in order to produce a molding composition which meets the requirements of present day molding operations.

A difficulty which has confronted me and caused me to make a large number of experiments is that which I term over-curing. As previously indicated there must be a balanced condition in that the resin must be very fusible when initiallyheated but must set rapidly in order to be removed from the mold in a hot condition. These two requirements are inimical. Extreme fusibility results in too slow curing or setting. To obtain successful results in a commercial wa the details which I hereinafter set fort should be followed with care.

, The difliculty of overcuring manifests itself by a floury surface, leading one to conclude that there is an insufiicient amount of resin to coat the particles or fibres of the filler.

Yet this surface impairment may occur even when the resin is present in predominating amount. The difliculty apparently is due to contact of some of the particles with the hot mold for too long a time prior to the application of pressure. The heat causes reaction of the resin before the particles have been brought into close contact by pressing resulting in the resin coating becoming glazed and set. The particles of the composition therefore do not fuse. and weld together 'when pressure is applied. This defect may not appear when using small molds but is frequently observed with larger molds which are more difiicult to heat evenly. Over-curing may then be expected at the points where the transmission of heat is greatest.

Over-curing may be caused by too long a time of heating together of the reacting raw materials or too high a temperature at this stage, or because too long a time or too high a temperature is used in drying. The presence of an excessive proportion of filler also sometimes gives an appearance somewhat similar to over-curing effects.

The strength of the molded specimen usually increases up to a certain point with increasing additions of filler. centage of filler, as is the case with many Too low a per- Nil) other resins, hard rubber and the like, fails to yield a product of the desired commercial properties. Too large a proportion of filler also is disadvantageous especially in securing a good flow of the resin and coverage of the filler. The maximum amount of filler of any given type may be determined by making simple strength tests which need not be outlined here.

Another difficulty which may arise from time to time is that of sticking to the mold. This may be remedied by the addition of one or two per cent of a water insoluble soap such as aluminum palmitate, magnesium or zinc stearate and the like. The metallic soap should be added in the form of a very fine powder to the batch at the time of mixing resin and filler, or it may be ground with the finished molding composition to flour the particles with this substance.

In some cases especially when using lime, barium or magnesium oxides or hydrates as the base the addition of a water-soluble soap such as ordinary laundry soap permits of the formation of an insoluble soap and minimizes sticking.

The proportion of formaldehyde should be carefully ad usted. Ordinarily aqueous formaldehyde having a content of 37 to 40 per cent of actual formaldehyde may be employed with cresol in the proportion of about equal parts by weight. Rarely should it be less, although in some cases 90 parts or thereabouts of formaldehyde solution may be used to 100 parts of cresol. In the presence of a full mol. of magnesium base the formaldehyde combines very rapidly during the heating or cooking operation so that in the course of a few minutes the odor of formaldehyde disappears. However. some formaldehyde may be liberated or eliminated during drying and when a vacuum dryer is employed such formaldehyde may be recovered if the quantity warrants.

The following illustrations serve to'show the effect of the various factors mentioned above which enter into the production of a successful commercial molding composition and plainly illustrate a number of differences between cresol (cresylic acid) and phenol.

The proportions given are by weight.

In Table 1 the resin obtained from different phenolic bodies is shown. The experiments as nearly as possible were'carried out under the same conditions, merely varying the time'that the solution is boiled in each case. It will be noted that in the preparation of the cresol or tar acid resin boiling the constituents for only 20 minutes and subsequently drying, resulted in an over-cured product. whereas when the phenol solution was boiled for 45 minutes a resin resulted having satisfactory molding properties and it required 75 minutes boiling to affect the flow of the resin made from phenol.

Table 1.

No 3192 3&2 3193 lslnd oi pm! Phenol 10o Tar acid 100 Phenol 10o Formalde- 100 100 110.

iyde. Basie mu- MgO 20 MgO 20 MgO 20.

term] Time of 75 minutes 20 minutes 45 minutes.

heating. 'Iemp. o l Boiling Boiling. Boiling.

heating. Stateot Turbid.No Turbid. No 'Iurbidlse solution. separation. separation. separation. Dryipg 0011- In vacuo to 90 In vacuo to 90 In vacuo to l ditlons. G. with filler. C. with filler. C. with filler. Results on I n s 11 ill or e n t Poor flow, over- Good flow, cured molding. flow cured in cured at 160 in 4 min. at 4 min. at 160 C. molded ar- 160 C. Goo" 0. Good surticle had unsurface. face. coated fibres on surface.

In the above table and in the followii tables the word tar acid is used to denote n'uxture of cresols containing approximate per cent orthocresol and per cent met paracrcsol.

The effect of varying the base is shown iuTable 2, some of the salts of magnesium being given for purposes of comparison.

Table 2.

Kind of phenolic Phenol 100 Phenol 100 Phenol 100 body Formalde- 100 106 100.

hydo. Balsa: mete- MgOO; 45 MgO 20 MgS0++H O ria 130. Time or 2hours lhour lhour.

heating. Temp. of Boiling Boiling Boiling.

heating. State of so- Turbjd with pre- Turbid. No sep- Separated into lutlon. cipitate. arution. two layers. No resin formation I observed. Drying eon- With filler in With filler in 'tions. vacuo to 00 C. vacuo to 00 (1. Results on Did not cure in Good llow,eured molding. 7 min. at 100 in less than 4 0. good flow, min. at 100 good surface. 0. Good sur- Softened on face, hard, did heating. not soften on heating.

Table 2. Continued.)

Kind of Metaparacresol phenolic Tar acid 100 'lar acid 100 i 100 body I i Fgrrgnlde- 100 100 81 y e. Basic rna- Mg(OH)z 28.-.- Ca(OH)z+ MgO 18 terial. Mg(0l.[)| 27}. Time 01 30min 20min 50min heating. Temp. of 00-95 C 90-95 C C heating. State of Turbid. No.sep- Turbid Turbid.

solution. aration. f Drying cori- With filler to 00 With filler to 70 With filler to ditions. C. in vacuo. C. in vacuo. I C. in vacuo. Results on Goodllow,cured Poor How, resin Poor flow, overmolding. in 5 min. at overcnred at cured at 160 100 0. Good 100 0. fibresi 0., fibres exsuriaoe. exposed on posed on sursurlaee of face of molded molded nr-. article. ticle. I

Table 3 plainly sh ing composition obtained ows the effect of do. The mo with less than 90 parts of commercial formaldehyde to 100 varying be noted that the flow of the molding composition was poor temperature were heated, the

high

in every case, due to the at which the constituents fiect of which is shown in parts 01': cresol being under-cured. It will Table 5.

Table 8.

d 01 Formal- Basic Time of Temp. of State Drying No. phefillc body dehyde material heating heating solution conditions Results 00 M 0 20 20mlnntes. 90-95 C. Turbid. No In vacuo to 75 Poor flow, cured in less than min. I 3272 fi ol f g separation. C. with filler. No fibres exposed on surface. Matt M 02c t sac-95 o Tur s No In v c o to 75 P ir fl dv v ii' ii iie cured t (1 minu es. 01'. a u l n r a on o 3255 acid 100 8 separation. C. with tiller. 5 min. sit 160 0. Cresol given ofi M 0 20min t 90-95 C '1 b'd N I t 75 P l l lmdliding d dryidlg't d f 75 20 u esnr 1 o n vacuo o 001 ow so an ercure a on 0 3256 Tu acid mo 8 separation; C. with tiller. 5 min. at 160 C. Cresol given oil during molding and drgilng 3257 Tar acid 100..- 90 MgO 20 20 minutes. 90-05 C. Turbld. No In vacuo to 75 Poor flow, disc cured wit n 5 min. at 0 20 20ml t 9095 C 'rfii i li o In vii ii d 3o 7? m ll l ntfl w r ured t 160 0 id 1 100 M nu es. l c1 0 ove c a 3253 Tar ac 00 8 separation. C. with filler. glisc having uiicoeted fibres on surace.

In order to illustrate the eiiect of varying the time and temperature of heating the reaction mixture, and the resinous solution,

'ven. The examples as without filler as it is at the temperature Tables 4, 5 and 6 are given are of the resin this point in the of drying production of molding compositions that the results are mostly plainly shown. An exception is experiment 3258 which is given to illustrate the length of time reqmred to effect separation of the resinous and aqueous layers with resultant undesirable efiect.

Table 1;.

Kind gf gg Tar acid 100 Metaparacresol 100 Metaparaeresol 100 Metaparacresol 100 Formaldehyde Basic materie MgQ M20 '10 Mg() 20 Time of heating 90 min 10 mm.- mm-. min. Tamp oiheating- 90-95" C C C 70 0. State of solution Separated into two layers. Turbid. separation.... Turbid. No separation- Turbld. No separation. Drying conditions..- In filviacuo to C. with Infiilrlecuo to 70 0. without lnflfiacuo to 70 0. without In vacuo to 70 0'. without er. er. er. State of dried resin Viscous oil Thick viscous liquid Pasty solid. Results onmolding. Poor flow. Over-cured at Flows very freely, cured Flows very freely, cured Flows very freely cured in 0 0. Disc had unin less than 5 minutes at in less than 5 minutes at less than 5 minutes at coated fibres on surface. 160 0. 160 0. 160 C.

Table 5. Table 6.

' Non 3285 3285 3285 No m 3285 3285 Kind of Meta Kind of paraerescl Metaparacresol Metaparacresol Metaparacrcsol Meteparacreeol Metaparacresol plalaoylic 100 00 53 100 100 100 Formalde- 00 90. Formalde- 00 '90 00.

hyde. hyde. B s ic ma- MgO 20 MgO 20. Basic mate- MgO 20 MgO 20.

n r1 Time 0! 30min.... 30min. Time of 30min 30min.

heating heating. Temp. 0! 70 0-.---- 90 C. Temp.of 70C-- 70C- 70C.

heating heating. State of 30- T urbi d N o Turb 1 d N o T u r b i d N 0 State of so- Turbid. No Turbid. No Turbid. No lution. separation. separation. separation. lution. separation. separation. separation. Drying con- In vacuo to 90 In vacuo to 90 In vacuo to 00 Drying con- In vacuo to 70 In vacuo to 80 In vacuo to 90 ditions. C. without C. without C. without ditions. 0. without C. without 0. without fl1ler. filler. Q filler. filler. filler. filler. S t a t e of Soil solid Hard solid... Hard brittle S t a t e of Thick viscous Pasty solid.-.... Soft solid.

giried ressolid. 41 r i e d liquid. 11. resin. Results on Slight flow Very slight flow, No flow, over- Results on Flows very free- Flows, freely Slight llow,cured molding. cured in less cured in less cured at molding. 1y, cured in cured in less in less than 5 than 5 minthan 3 mm- 0. less than 5 than 5 min. at min. at 160 C. utes at 160 C. utes at 160 0. min. at 160 0. 160 C.

In Table 7 is shown the effect of drying a composition made by incorporating the aqueous resin solution with wood flour and .then drying in vacuo in comparison to a composition solution 1n resin to the Table 7.

\ No -I 3281 3202 3280 3280 d of Phenolic Meta l 75. Tar Metaparacmsol 76. Tar Metaparecresol 75. Tar Metaparacresol 76. Tar

Km body W25 acid 25 acid 2!; acid 25 Formaldehyde 100 100 100 100. Basic material M30 20 M3020 M3020 Mg0 20 Time oiheating-.- 20min 20min 20 min 20mm, Temp. of heating. 0.. C 70 C 0.

State otsolution- Turbid. No separat1on.- Turbld. No separatlon....- Turbld. No separation... Turbid. No separation. Drying conditions... In vacuo to 78 C. then In vacuo to 90 C then In vacuo to 70 C. with In vacuo to 80 C. with added filler. added filler. ler. r.

Treatment of com- Exposed to air over night Exposed to air over night. Exposed to air over night sition. Rgs ults on molding" Good flow, cured in 5 Fair flow, indications of Fairflow, cured in5minutes Slight flow, over-cured at minutes at 160 C. overcuring at 160 C. at 160 C Fair surface 160 0. Fair surface Good surface. Some pieces had fibres exhaving a matt finish. having matt finish and posed on surface. some exposed fibres.

Upon analysis of the foregoing tables it is evident that with phenol it is possible to obtain a molding composition having suitable properties even with a relatively considerable variation in conditions using a full mol. of base. With cresol (cresvlie acid) on the other hand a short period of heating to the boiling point may cause the formation of an over-cured product. Using smaller quantities of a base such as magnesium oxide in for example one-fifth equimolecular proportions, while it is true that a resinous material is obtain a molding composition prepared from this resin does not cure within the time required in a commercial molding establishment. As shown in Table 2 this under-curing of the molding composition Within the required time is also true when a compound of the type of magnesium carbonate is used. The use of a salt of magnesium of the type of magnesium sulphate results in little or no resin formation. With the hydroxide of magnesium a satisfactory resin for the pre aration of molding composition is readily o tained when the temperature, at which the initial reaction is carried out, is maintained at -95 0. However by merely boiling the constituents in the same proportions an over-cured product results. The conditions for preparation of molding composition where the resin is prepared using hydrated dolomitic lime as the base are again different. As shown in Experiment 3170 the composition prepared according to the conditions given resulted in an over-cured product even though the conditions in heating and drying were somewhat modified to minimize over-curing. With magnesium oxide the same condition holds true as will be discussed later. The roportion of formaldehyde used to the p enolio body affects the curing time of the resulting composition seriously as is shown in Table 3. The conditions in all of these experiments were such as to give an over-cured product provided sufliflow very freely and in cient formaldeh do was present to combine with the phenol but as noted in Table 3 when the proportion of formaldehyde was reduced below 90 parts of formaldehyde to parts of the phenolic body under-curing resulted and free cresol was given off during the molding operation.

The viscosity or consistency of the resin obtained by varying the time of heating the reacting materials is noted in Table 4 and is directly proportional tothe time of heating. I must reiterate that the composition should order to accomplish this it-is necessary that the resinous constituents thereof should be liquid at a practical molding temperature, for example, -17 0 C. so as to thoroughly wet the filler and then set to a thermo-rigid body. Resins may be tested in the press for flouring and setting qualities b omitting the filler in the first instance. have found the following to hold true, namel a resin which without filler becomes sufliciently liquid at sav C. to flow out along the narrow space between plunger and case of the mold when pressure is first applied and remains liquid for 1 or 2 minutes and then becomes so viscous that a pressure of 1000 pounds per square inch can be applied without forcing any more resin from the mold, finally setting (in thickness of say to 4 inch) to a thermo-rigid body within minutes, is suitable for the production of a molding composition.

Varying the time of heating durin initial reaction when perparing the resin at eats the flowing property of the resin seriously. By heating initially 30 minutes or more at 70 C. the resin without filler flowed ver freel in one case but when incorporated with filler and the composition subsequently molded an article was obtained having the appearance of uncoated fibres at the surface and lacking in strength.

The temperature at which the resinous material or the composition is dried to remove 11-1011 with cresol.

water or volatile solvent reduces the flowing properties more or less in inverse ratio to the temperature and accelerates the curing properties of the resin more or less proportionally to the temperature. In table 5 the effect of temperature at which the material is reacted is shown. The drying conditions here were higher than were subsequently proven to be practical for the composition in question but the data serve to show the effect of the temperature of intial heating. In Table 6 the eflect of dryin temperature above referred to is shown an the consistency of the resulting resin may be expressed roughly ,as inversely proportional to the drying temperature.

In any previous publication coming to my knowledge no great stress has been laid on whether a filler should be added to the resinous solution before or after the moisture or solvent has been removed but I have found that this plays a not unimportant part in the production of a successful molding composi- For example in Table 1 Exeriment 3193 where phenol was reacted with formaldehyde and magnesium oxide and then incorporated with the wood flour filler and dried a satisfactory molding composition was obtained. In Table 7 is shown the deleterious effect of incorporating the filler before drying of the resinous solution. In Experiment 3281 in which the resin was first dried then mixed with the filler a molding composition having satisfactory properties was obtained, while as shown in Experiment 3280 the addition of the filler to the solution of the resin and then drying-resulted in a composition having unsatisfactory properties even though the temperature of drying the composition was lower than when the resin was first dried and then mixed with the filler.

As an illustration of the preferred method of preparing molding com osition the ollowing is given. 90 parts ormaldehyde, 40 percent solution, was ground with 20 parts of magnesium oxide in a pebble mill for 2 hours. The ground mixture was then added to 100 parts metaparacresol and the mixture heated for 20 minutes maintaining the temperature at 70 C. An exothermic reaction took place and it was necessary to cool the mixture through most of the heating period. he resinous solution was placed in a vacuum dryer and evaporated under 28 inches vacuum until the temperature of the resinous mass reached 70 C. The hot viscous resinous material was then mixed with an equal weight of wood flour in a lVerner-P-fieiderer mixer for one hour or untilthe particles of the wood flour had been thoroughly coated with the resin. A small quantity of moisture remained in the composition and this was removed by allowing the composition to stand exposed to the dry air at room temperature for 12 hours. The composition molded successfully at a press temperature of 160 C. flowing freely, curing to a thermo-rigid body within 5 minutes and forming a good fin.

The presence of orthocresol in the cresylic body used for the preparation of a resin modifies the flowing qualities and affects the curing properties of the resin seriously. Orthocresol, when reacted with an equal amount of formaldehyde and a' molecular proportion of ground magnesium oxide, ave a resin which upon molding flowed so freely that it was forced out of an ordinarymold without indications of setting. When calcium oxide is used in place of the magnesium oxide as the basic material the resin obtained flowed very freely but set after a prolonged period of heating, forming a porous infusible resin which can readily be powdered. The presence of orthocresol in commercial cresol (cresylic acid) must therefore be taken into consideration but under the proper conditions a practical molding composition can be obtained. For example 100 parts of formaldehyde 40 per cent solution was ground with 20 rams 0 magnesium oxide in a pebble mill or 2 hours and the resulting mixture added to 100 parts of commercial cresylic acid contaming parts of orthocresol, parts of metacresol, and 25 parts of paracresol. The

mixture was maintained at a temperature of C. for a period of 20 minutes and. the resulting resinous solution dried in a vacuum dryer under 28 inches vacuum until the temperature of the resin reached 70 C. The dried resin was mixedwith an equal weight of wood flour in a Werner-Pfleiderer mixer for a period of 1 hour. The composition was then air-dried at room temperature for 12 hours. Upon molding, this composition was found to stick slightly to the mold but otherwise had the required flow and curing time, namely 5 minutes. Sticking of the composition to the mold may be overcome by addition of 1 per cent of aluminum palmitate and this can be added during the mixture of the dried resin and the wood flour or may be added subsequently by grinding the dried confiposition with the palmitate in a pebble m1 It may of course be possible to produce a molded article from orthocresol by the use of the so-called bakelizer where the resin is heated under pressure for an impractical length of time but for the purposes of the resent invention involving high speed moldmg the use of orthocresol alone is not desirable.

In the preferredform ofmy invention a resin is obtained by reacting on meta and para cresol (with or without 5 or 10 per cent, more or less, of orthocresol) with approximately an equal amount of formaldehyde solution (40 per cent) ground with a base, preferably in excess of 1; mol. (calculated on eresol used), preferably more nearly approxi- Inn mating a full mol. in the case of magnesium oxide or hydrate, the time and temperature of heating and drying being regulated as described to secure a very flowable product on press-heating but which sets in a fewminutes at l50170 C. to a thermo-rigid body; such resin being preferably incorporated with a porous filler, without substantially impregnating the latter; whereby a maximum amount of filler may be incorporated; such composition when molded in a heated mold at 160 0. being capable of flowing readily and because of this property of extruding to a slight extent along the movable joints of said mold, thus forming a thin, somewhat flexible fin; said composition when thus shaped intoarticles having a thickness of to of an inch being capable of setting to a rigid state at the molding temperature of 150170 C. In a period of less than seven minutes.

What I claim is r 1. In the process of making resinous mold ing composition the step which comprises Iglriiding magnesium oxide with formalde- 2. In the process of making molding composition, the steps which comprise reacting on cresylic acid containing largely meta and para cresol, with a ground-together reagent of magnesium oxide and aqueous formaldehyde, drying the reaction product, the conditions during the reaction and drying steps being such as to time of treatment and temperature, as to form a resin which is suificient-l fluid when warm to be mixed with filling material, incorporating the warm fluid resin with filler to substantially coat the latter and adding a small amount of a compound capable of preventing sticking in the mold during molding.

3. In the process of making resinous molding composition, the step which comprises grinding magnesium oxide with formaldehyde until a cream is formed.

4. In the process of making resinous, molding composition, the steps which comprise grinding magnesium oxide with formaldehyde until a cream is formed, and converting such cream into a paste.

5. A process of making resinous material which comprises grinding magnesium oxide with formaldehyde, and reacting such ground mixture with cresylic acid.

6. A process of making resinous material which comprises grinding magnesium oxide with formaldehyde to form a cream, and reacting such cream with a cresol.

7. A composition for use in making resinous material which comprises magnesium oxide ground with formaldehyde.

8. A composition for use in making resinous material which comprises magnesium oxide ground with formaldehyde to form a cream.

- HARRY M. WEBER. 

